And finally... my question.Assorted Plants, some of which are doing better than others :/I'm not sure exactly what I have, but some if if is doing MUCH better than the others.
Anubis, Java Moss, Amazon Sword... 4-5 others...
I've tried everything. I bought a co2 cylendar, I bought root tabs.
Some of the plants are pearling on a daily basis, and some are straight up losing leaves...
What gives?

Perhaps I just need to be better educated and pick the right plants?

Is my Tank overstocked?
Is that causing the plants to die?
Do I not have enough Lighting?
Is the moss sucking up all the co2?
Should I be testing more? For what?

Having reviewed your information and photos, my initial thought is that there are insufficient nutrients. I'll explain; some of this you may already know, but I don't know if you do or not, so I will be detailed so it is clear.

Plants grow by photosynthesis, and to photosynthesize they need light and 17 nutrients. Provided all are present, plants will photosynthesize to the max. But as soon as something is no longer available, photosynthesis slows or may stop altogether. This is called the law of minimum. The limiting factor in an aquarium should always be the light.

You have plenty of light, perhaps too much, but you also have CO2 diffusion. But without the other 16 nutrients, plants can't make use of all that light and the CO2. This is what is wrong with the moss I believe, there is too much light (moss prefers less light) with insufficient nutrients.

Some nutrients occur naturally in the aquarium, especially with fish. Nitrogen is a major nutrient, which plants prefer in the form of ammonium which comes from the ammonia released by fish and bacterial processes in the substrate that break down organics. Oxygen and hydrogen (water) obviously occur naturally.

Some nutrients enter via fish food, and will usually end up in the organics in the substrate. Some enter via the water, such as calcium, magnesium, zinc, nickel, iron, manganese, sulfur, etc; but depending how many of each of these is in the tap water, the amount actually available for plants can be quite limited.

In a natural or low-tech system, with no added CO2 [which in such a system occurs naturally from fish respiration and even more from the decomposition of organics in the substrate], it may or may not be necessary to add nutrients in the form of fertilizers. Substrate (root) tabs may be sufficient, but some plants may not benefit if they are not rooted in the substrate. A liquid fertilizer that is complete is usually sufficient. Something like Flourish Comprehensive Supplement, which is my choice. Plant growth in such a natural system will be slower, but still steady.

Once you up the light intensity and add diffused CO2, the need for the other nutrients increases considerably, and sufficient will never be available without increased supplementation. High-tech systems often add nutrients daily, either as liquid preparations or using dry fertilizers that the aquarist mixes with water. Without this, the plants will struggle, as they are here. Root tabs usually are insufficient in themselves, since they, like many liquid fertilizer preparations, are basically intended to supplement natural systems that just need some boosting, so to speak.

You have two choices. One is to remove the CO2 and reduce the light, and switch to a more natural system. The other is to retain the light and CO2 but add daily nutrient supplements.

My approach has always been natural or low-tech, so if you want to go that route, I would be happy to guide you; the photos of my tanks [under "Aquariums" below my name on the left] illustrate this approach, which I find sufficient for my needs. I've no direct experience with the high-tech approach, but we have other members who have, and they will be able to suggest feasible fertilization schemes to balance.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

I agree with Bryon. You set the bar for growth too high by having CO2 diffused, so now they aren't getting enough of the alternative nutrients. Root tabs will NOT be enough, I have experienced this myself directly. You will need both root tabs and a composite mixture of alternative fertilizers, both liquid and solid most likely. The EASIEST and most RELIABLE solution to your plant problem is to remove the CO2. The plants will perk up and they will grow their natural rate, which should still be fairly acceptable. I live for plants and my new aquarium is hugely plants (I should be getting pictures when I get around to it).

I had a suspicion that it may have been tied to nutrients, hence the root tabs...
You're post was extremely insightful, it all makes sense and all the symptoms fit.

Since I've already invested in the tank and regulator, I want to see if I can make my current setup work, so I went out and bought some Flourish and some API Leaf Zone. I'm going to try regular dosing with those guys and see if anything improves.

Thanks again. I'll search the forums a bit for recommendations on ferts since I'm sure it's been discussed many times before.

What about substrate? I've seen fancy bags of substrate touting crazy benefits, but I've read that they're just coated gravel and the benefits eventually disappear after several water changes.

Is my gravel sufficient? I've seen Laurite mentioned several places, but apparently it can be a pain to get into an established tank without clouding the heck out of the water-column.
(Some methods I've seen include freezing it into cubes, baking it into balls, etc)

Is my gravel enough?

Your tanks are incredible by the way.
Making me reconsider the co2 tank for sure....

Fingers crossed that the liquid fertilizers help.
If not, I'll be bombarding you with questions about the natural route.

Forgo the fancy substrate, it's not worth the money - gravel would work out just fine or something fine like sand. For the exact reasons you yourself listed, you hit the nail on the head with that one.Posted via Mobile Device

most people use dry fertilizer for "high tech" tanks a it is cheaper in the long run. Since you are using more fertilizers with those setups. If you find that the two fertilizers that you bought are still not working check out dry fertilizer methods.

I'm going to start with these pre-mixed solutions, but can anyone recommend a good dry fertilizer mix I can buy and make on my own?
I know the more advanced users pick and choose chemicals based on tank needs, but I'm talking about a pre-mixed powder I can use to basically emulate what Flourish and Leaf Zone do? (Dry ferts for noobz)

I'll work my way up to "chemist" level, but can anyone share a nice pre-mixed powder?
It seems so silly spending 8 dollars on 98.7% ionized water.

If I was you I would take out your carbon pad/cartridge continue to use the fertilizer you have bought already and wait a couple of weeks and see if there is any improvement. If not then you can try something different. During that time study up on dry fertilizer. Besides it going to take a couple of weeks to see any difference in your plants especially if they are slow growers no matter what you are using for fertilizer. Also that premix would probably work. I dunno as I have only seen dosing regimes that show dosing those on different days not all at once. I am still learning that method myself. I want to start using those at some point.